Escapement mechanism for typewriters



. June 20, 1944. G. PREzloso ESCAPEMENT MECHANISM FOR TYPEWRITERS Filed Aug. 7 1941 ws/wv@ i Gaweppeezwso,

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Patented June 20, 1944 Y TYPEWRITEns Giuseppe Prezioso, Yverdon, Switzerland, assignor to E.Paillard etCie S. A.Yverdon, Switzer-J` f land, a corporation ci" Switzerland e Application August 7,1941is In Switzerland February (i,v 194i 5 Qlaims.

Known escapement mechanisms for typeWrit-"f ling, adding and similar machines generally comprise a pinion which meshes with the rack fitted on the carriage, said pinion being secured'to a shaft and actuating a ratchet Wheel Which coolperates with retaining and'escapement'pawls.

So far as strength, rapidity, accuracy, silence and touch safety are concerned, the present requirements are such that known escap'ement mechanisms cannot meet them all, and 'compromise solutions had to be adopted. Thus for eX- ample a very quick acting escapement mechanism is generally lesssilentand probably less accurate than an escapement mechanism allowing of a reduced touch speed. -v

A major disadvantage of :known escapement y mustv hold the same momentarily in its position while the key is depressed. Y

When stresses on -both pawlsare smalLthey 'can operate on teeth having the sameoutline.

However, for quite a number of years now, it'has been customary practice to provide each-tooth with two diierent engaging surfaces, thetwo pawls being then arranged on the oppositefsides of the ratchet wheel and engaging the 'side faces of said wheel. 'I This construction made it possible to increase touch swiftness. As requirements regarding noiselessness have been growing more'and more, attempts were made to. render such mechanisms silent by the provision of elastic cushions or else respective by ,mounting both pawls Lon a oating'block.

However all the foregoing improvements rendered such mechanisms very complicated and Weak in structure especially for large size machines 'which are employed for office work and 'consequently subjected to heavy duty and vwhich consequently are not very accessible and very delicate in .their adjustment Without permitting a complete `vfullment ofthe above-citedrequirements,`

. The present inventionV hasfor its primaryobject to provide an improved escapementl mechanism fortypewriting, adding and other' similar machines, Said mechanism being adaptedfto obvlate the' aforesaid disadvantages while satisfying all practicalY requirements iand ensuring ai great operationalsimplification andproper touchsaiety over a widerange' of typewriting speeds.

Another object,v of" the 'inventionis to provide an improved escapementmech'anisinior typewriting and similar machinesfthe elements of vwhich are Vso arranged as to provide proper clearance.

between themas Well as easy` accessibility.V 1' 'Another object' still' ofthe'invention iis to provide" an improved: esc'apen'ient 1 mechanism! for typewriters, comprising fa pair of independently pivoted and guided pawls or` dogs having 'difierentiated functions andcooperating'wi'tha pair of -ratchetwheels, the arrangement being such as to permitquickl and easy adjustment and control of'eachipawl- Y f i -Aiurther .object ofthe invention is' to provide an improved vescapement mechanismA whose cooperating-members have surfaces specially adapted for avoiding rattle sol that-the general 'operation of the typewriter is substantially noiselessvwhile the movement of the carriage remainsquick'- and .apcqrate' i "I "f3 j "jf," Still-a further obj-ectgofthe invention is to provide an improved escapement mechanism so built as .to permit"` the grouping *upon` a unitaryl block frame LVof allthe operating members for vthe esapement. mechanism, thev decimal tabulator, the means for positioningand'withdrawing tabulator stops upon `,the carriage; the brake, the carriage 0' free release, the papercarriagebraked release, the `,carriage return, and meansjadapted to eliminate anyrattle Adi'iring Vthe return lmovement. of said carriage,` means tof provide 'al variable spacing, and'means Atofcontrojl' vthe escapement action by hfspacebar'ofthe ,typewritenV ,Y r I With th'ese'and 'such other objects jin View. as Will-appear hereafterjthe invention'y comprises vthe novel construction, disposition'and combination of elements that now ,be described in detaiLwith reference tothe accompanying drawirgj'showing b'yiwaiyof "example inperspective a suitablel constructional y,form fofA the' improved escapemeiitmehenm-@applied t0 a typewritn In the lSle' ligure formingA apart of the lpresent disclosureionly those elements whichare nec- ,essar'yl VforapropeifY"understanding of the inventionfhavegbeen'shown, vthe other known elementsgbeing obvious to thoseskilled in the art. j filtri-the soleigure,` reference character Ildesighates-a pinion adaptedto `ycome into meshing engagement with a rack of" known form fitted on the machine carriage (not Hshown) which may have any'conventional;construction. The machine has theusual universal bar (no tshown). Thepimerigl1isscuz1tedto e Stub shaft 2 tt/meh are rigidly xed a pair of ratchet Wheels 3, 4. The pinion I is secured to one end of the shaft 2, While the ratchet wheels are secured to its middle portion. The free end of the stub shaft 2 is pivoted in a bearing-like recess formed in an escapement frame G. i:

In order to impart greater rigidityto the assembly and to properly hold the shaft 2 in vertical position, the frame 6 comprises a further bearin'"`g.`

situated under the pinion I. .y

The second ratchet Wheel 4 has spur gearing and cooperates with a retaining pawl 8 pivoted on a stud 9 mounted on armember. I'0.slidably received in recesses I I formedin -the'rame6-- The retaining pawl 8 is urged by a-fs'pring l2 fixed thereto at one end and attached at its other end to the sliding member fIfILySaid spring tends to push the retaining pawl Sinto engagement with the second ratchet iwhe'el4. The sliding member I0 is urged by a tension spring 5 in a direction to the right asviewed in the drawing'.- The stroke of themember I0 is .limited bythe fact that its end I3 urged by the spring 5 contacts pivoted stops 44, 45 or the face 5I of a block 85 onwhich are pivoted said stops. Swinging of stops 44, 45 into or out of the sliding path of sliding member ,I0 may be directly controlled, or controlled by the depression of1a key or. through a .universal bar. rIhe stops 44, 45 are held in the position as shown in the drawing by springs v44a,.45a, and are voperated by traction rods 44h, 45h. The arrangement is such that the stop 44 can move-independently by itself while the stop 45 can only movev Kby carrying along with it the companion stop '44 through the medium of a -lug 45ctffInforder to lessen rattle, the end `face VI3of the sliding member IU may be lined with` a resi-lient or sound-absorbing substance. v f n c n The retaining pawl L8 is provided withjan operating member which comprises a *stud I4 adapted, when a key :ls `depressed, toengage an arm I 5 secured to an-auxilia-ry shaft I6 arranged parallel to the sliding member I8. The auxiliary'.V shaft I6 has rigidly fixed thereto the following 'auxiliary shaft I6 'is vsubjectedim 'the torsional urging of a helical spring I9` 'the tendency of which is, on the one hand, to 'constantly hold the roller II in contact with'th'e main 'universal bar and, on the other handgto keep the dog I8 clear vof the first ratchetwheel. The auxiliary shaft I8 pivots on adjustable headstocks 20 housed in suitable recesses of 'the frame '6.

The dog of the escapement pawl I8 Vis mounted on the 4block Ilia through the intermediary of a piece of noise-reducing material [6b. The movement of the sliding` 'irrieir'iber IIJ is limited in one direction by a diskv I3a `of Anoise-reducing material xed on its extremity and being supported on a. n-xed part, and limited inl the ether direction by a piece I3l of noise-reducing material covering its ektremity and being vsupported on one ofv the stops, 44, 45, or Athe block 5I. u

tongue 29 secured to a yoke-shaped piece 38 The dog l8 4may 'also be pivoted at 3l on the side faces of the frame 6 is actuated by a lever adapted to unlock the carriage (not shown) and acts through the medium of levers32, 33, on the retaining pawl 8 against the action of the spring I2 to disengage the retaining pawl 8 from the'secondratchet wheel 4. The lever 33 is pulled back toits position of rest by a spring 61.

'Ihe rear face of the frame 5 is provided with vertical grooves in which can slide members .adapted to stop the decimal tabulator, said members comprising tongues 35 actuated in the upwarddirection by means of certain keys of the keyboard (not shown) and levers pivotally connected at 36. Each tongue 35 has a nose 40 adapted to engage and actuate a tabulator universal bar 31 having a yoke shape and pivoted on pintle 38 on both side faces of the frame 6. The tabulator universal bar 3'I actuates the following members, namely: i

(a) The retaining pawl 8 against the action of ,its return spring I2 by pressing the lever 33, thus freeing the carriage whichis then quickly shifted under thev influence of its return spring;

(b) A brake constituted by a pair of shoes 4I which clamp between them a stub shaft 42 secured to a toothed. Wheel 34. The operation of this brake is eifected under the control of the tabulator universal bar 3'I by kbringing the toothed wheel 34 into engagement with an annular gear 39 secured to the shaft 2. A return spring 69 urges the .brake-carrier 'I0 intocontact with a portion of the tabulator universal bar3I. A.1. u On the one end of the pin 38 is rigidly mounted an operating lever by which the tabulator universal bar 3l is operated when `a keyffoffthe keyboard is depressed so 'as to releasethe carriage (by bringing the brake into actionlinde- Ypendently ofthe operative positionedtabulator stops.

Obviously the control :of these several-mem bers by the tabulator universal bar l3'I may be Iarranged to suit requirements in a Wayfdifferent from the one described. For example the brake may be controlled through the medium lof the spring 68 with aviewto facilitating adjustments. f- The rear face of the frame 6 is provided, 'moreover with controls for'proper positioning and spacing of these stops-*Which are supported by the carriage vand are adapted to engage with `the tongues 35 of the decimal tabulator. The control for positioningthe stops is performed by means of a finger-shaped member 46 pivoted lat 8| `and actuated by a special key ofthe keyboard through a Vbar (not shown) pivotally connected at 41. The finger 46 pushes the :stopin front of which it is into operative position; The control of the withdrawal vof the stopsisen- 'sured by a stud 48 also pivoted at 8l andfad'a'pted to bring back the stopsl to their inoperative ,poe sition. The stud 48 is actuated from a keyjp'f the keyboard through themedium Vof a bar *"(not shown) pivotally connected at 82. 1 j.) f

4In order to obviate therattle of the 'escape'-4 me'nt paWl 8 as it rubs the teeth of secondratche't Wheel 4 during the return stroke ofthe carriage, a groove 54 is formed in said ratchet WheelJ`4`. In said groove is 'received 'a wire ring 'member 55 elastically clamped 'against its'bottom. O ne end 56 o'f 'this ring member is radially bent .outwardly. lWhen the l.stub shaft 2 rotates clock- Wise,'i. e. in the 'direction of normal paper feed of the'carriage, the'end "56 of the ring 'member 55 is frictionally" driven and abuts'a stud v5'I' on the frame 6.3 However, when the shaft 2 rotates -counter-clockwise, i. e. during the `return stroke of-the carriage,v said end 56 of 'the ring member 55 lcomes into :engagement with ay ramp I2 formed onthe pawl '8 and holds it out of contact with vthefs'econd ratchet wheel during the return stroke of thel carriage, thus avoiding vrattle'frvom the pawl'contacting the teeth of the second ratchet wheel:

The frame' G "is lpreferably constituted byk a vblock-structure formed with the ynecessary recesses :for accommodating the several memb-ers mounted thereon and enumerated in the foregoing description. Said block has a wide surface `50 formed Withmbores for the securing members -49. Between the base'surfaceof the block 6 and that formed on the machine frame 63 for receiving the same and also `betv/"een the securing members and theblock '6 areinterposed elastic lining pl-ates 6I (made for example of india rubber) the A'purposeof which 'isy to avoid rattle while at the same time ensuring perfect steadiness of the block or frame 5 on the machine frame 63. As will be easily understood, the operation of this improved escapement mechanism is substanvtially'similar to that o f an escapement mechanism tof knownjconstruction. However, it preseints very important advantages over the latter. Actually although at first sight it might appear thaty an escapement mechanism built according to the presentlinvention has a more intricate structure than 'an escapement mechanism of known type merely comprising a single ratchet wheel cooperating with a pair of pawls, the present invention involves in fact a great operational simplication.

Owing to the fact that there are provided two ratchet wheels, one cooperating with the escapement pawl, and another one cooperating with the retaining pawl, each set of teeth may be so shaped as to conform to the operation of the pawls. Thus no compromise need be resorted to, as is the case when there is only one ratchet wheel, for providing outlines ensuring a suicient touch safety for any given writing speed.

.As illustrated, the set of teeth of the ratchet wheel cooperating with the escapement pawl has a slanting outline so as to facilitate the release of the pawl which should retain the carriage momentarily only while the type bar is being struck. However, the teeth of the set cooperating with the retaining pawl have radial and vertical faces on which the pawl cannot slide.

Furthermore, owing to the provision of a pair of ratchet wheels, the orientation of said wheels and of the pawls cooperating therewith may be selected at will. In other words, it is then possible so to arrange the elements as to provide a proper clearance between them as well as an easy accessibility.

Each pawl is pivoted and guided independently of the other pawl, which permits to give them a rugged construction while allowing of an extraordinary rapid and easy adjustment. Moreover, as each pawl has proper clearance and accessibility, its control is very easy and can be achieved for example by means of a mere push rod. This obviates intricate and long mounting or assembling operations.

Moreover, as each pawl and the ratchet wheels may be oriented at will, such members may be so arranged as to provide sufficient clearance for lining the abutments with sound-absorbing material and providing them with wide contact suroted, it can be operated'for'itself.

faces. .Thisabsorbs the shocks and provides a noiseless 'escapement Without interfering' with .the rapidity and accuracy of the type bar stroke. The several ,members and particularly the pawls .may be so arranged asto constitute a rugged frame.

It thus becomes possible owingl to the present invention to provide a strong, accurate,

:rapid and noiseless escapement mechanism even 'fortypewriters or similar machines comprising #the heaviest type of carriage whic-h are in existence.

As,'moreover, each pawlis independently piv- It thus becomes possible to release the retaining pawl with- -out engaging the escapement pawl and to free -the carriage in that way. During the type bar stroke; the pawl 8 engages the following tooth corresponding to the stop 44 or the second tooth corresponding to the stop 45 or, alternatively, the third tooth corresponding to the block face 5|'. This permits manually to modify at will either by means of a key or automatically by means of one 'or' several universal blars'the'fspace between the types,l and to provide i1; single,A double or treble. vThis linvolves a particular advantage when typewriting must be effected with types having different widths as is the casewith gothic,'arabic for-other special types, also for typewriting titles, subtitles, addresses, captions etc. in which the intertype spaces must be larger t-han the normal space size. y

vThe reciprocatory motion of the retaining pawl rod is preferably tangential to the second details of an escapement mechanism according to the invention may be different from those described. Thus the bearings for the shaft 2 may be provided with balls or rollers, and the several members may be arranged on the frame 6 and shaped to suit requirements and to t the particular type of machine to which the mechanism is adaptable.

The other constructional details may also vary without departing from the scope of the subjoined claims.

What is claimed is:

1. In an escapement unit, a frame, a pinion shaft rotatably mounted on said frame, a driven pinion keyed on said shaft, an escapement ratchet Wheel having teeth with edges oblique to the radiun thereof, a retaining ratchet wheel having teeth with edges substantially radial, and an escapement pawl and a retaining pawl mounted independently on individual pivots and adapted to respectively engage said teeth of said ratchet wheels, said pawls being so arranged and operated that said escapement pawl normally engages said escapement ratchet wheel before said retaining pawl is released from said retaining ratchet wheel.

2. In an escapement unit, a frame, a pinion shaft rotatably mounted on said frame, a driven pinion keyed on said shaft, an escapement ratchet wheel having teeth with edges oblique to the radius thereof, a retaining ratchet wheel having teeth with edges substantially radial, a slide member slidably mounted on said frame, a retaining. pawl pivotally mounted on.: said slide member, and an escapement pawl pivotally mounted independently of said retaining pawl, said pawls being adapted to respectively engage said teeth of said ratchet Wheels, said pawls being'so. arranged and operated that said escapement pawl'normally engages said escapement ratchet Wheel .before said .retaining pawl is Vreleased from said retaining ratchet wheel.

3. In an escapement unit, a frame, a pinion shaft rotatably mounted on said frame, a driven pinion keyed on said shaft, an escapementrratchet Wheel having teeth With edges obliqueto theradius thereof, a retaining ratchet Wheel having teeth with Aedges substantially radial, a slide member` slidably mounted on said frame,a retaining pawl pivotally mounted on said slide member, an escapement pawl pivotally mounted independently of said .retaining pawl, said pawls being adapted to respectively engage said teeth of said ratchet Wheels, said pawls being so arranged and operated that said escapement pawl normally engages said escapementratchet wheel before said retaining pawl is released from said retaining ratchet Wheel, and a plurality of stop members selectively insertable in the path of travel of said slide member for controllably adjusting the maximum travel thereof.` v y Y 4. In an escapement unit, a frame, a pinion shaft rotatably mountedon said frame, a driven pinion keyed onsaid shaft, an escapement ratchet wheel having teeth with edges oblique to the radi- `us thereof, a retaining ratchet .wheel having teeth capement pawl pivotally mounted independently .of said Vretaining pawl, said pawls .being adapted to respectively engage said teeth of said ratchet Wheels, said pawls-beingso arranged and operated that said escapement` pawl nonnal, engages said escapement ratchet wheel before said retaining pawl is released from said retaining ratchet wheel, and an auxiliary shaft rotatably mounted parallel to said slide member and carrying means pivotally carrying said escapement pawl.

5. In an escapement unit, a frame., a pinion shaft rotatably mounted on said frame, a, driven pinion keyed on said shaft, an escapement ratchet Wheel having teeth with edges oblique to the radi*- us thereof, a retaining ratchet wheel .having teeth with edges substantially radial, a slide member slidably mounted on said frame, a .retaining pawl pivotally mounted on said slide member, an escapement pawl pivotally mounted independently of said retaining pawl, said pawls being adapted to respectively engage said teeth of said ratchet Wheels, and an auxiliary shaft rotatably mounted parallel to said slide member and carrying means pivotally carrying said escapement pawl, said pinion shaft, said auxiliary shaft, and the pivot which mounts said retaining pawl on said slide, al1 three being mutually perpendicular.

GIUSEPPE PREZIOSO. 

